This effective occult horror film was the final feature directed by the legendary Mario Bava. Daria Nicolodi gives her most convincing performance as Dora, who moves back into her old house with a new husband, Bruno (John Steiner), after spending time in a mental hospital. Strange things start happening, mostly involving her young son Marco (David Colin, Jr.), who seems to be possessed by the ghost of Dora's first husband Carlo, a heroin addict who committed suicide. Dora suffers from vivid hallucinations, and it soon becomes obvious that she is going completely mad, and that Bruno knows more about Carlo's death than he lets on. Bava stages the hallucination scenes with his trademark visual flair, and his son Lamberto Bava's script, co-written with Francesco Barbieri, Paola Brigenti and Dardano Sacchetti, handles Dora's shifting sense of reality with great skill and a subtlety rare for Italian horror films of the period.